OMAHA — Ask Caeleb Dressel what he remembers about the 2012 United States Olympic swimming trials, and he’ll talk about the spectacle: the tongues of fire on both sides of the pool and the rainbow waterfall from which each new Olympian rose on a platform like a red-white-and-blue apparition. He prefers to forget his performance in the pool: a tie for 145th, out of 167 finishers, in the 50-meter freestyle.
Four years later, Dressel, 19, is seeded second in the 50-meter freestyle behind the four-time Olympic medalist Nathan Adrian. Dressel, a multiple N.C.A.A. champion from the University of Florida, looks back at his experience competing at the 2012 trials — the sheer number of entrants, the sights, sounds and grandeur of the event — as the nudge he needed to become an Olympic contender.
“It makes you hungry when you see people making the team, and you’re just sitting in the stands thinking, Maybe four years from now I can be doing that,” he said.
The trials get underway Sunday at CenturyLink Center, where over 1,700 entrants will compete for fewer than 60 berths on the United States squad that will compete at the Rio Games in August.
Why are so many competing for so few spots?
Inclusiveness was not always part of the meet’s DNA. Twenty years ago, the event welcomed fewer swimmers than competed at the Atlanta Olympics. In 1996, there were, on average, 35 entrants in the women’s events and 27 in the men’s. The thinking then was that if only eight would race in the final for Olympic spots, no more than four heats were required to separate the best from the rest. In 1996, an up-and-coming teenager like Dressel would have experienced the trials from his couch at home.
The conscious decision to hold a fan-friendly, made-for-television spectacle during which a swim meet breaks out has reached full bloom this year, with the women’s events averaging 130 entries and the men’s events 124.
Backstroke, in particular, is not the best bet for getting ahead; there are 168 entries in the women’s 100 and 192 in the men’s.
It is not just the event fields that are supersized. Larger-than-life likenesses of the top Americans, including the freestyler Katie Ledecky, adorn the outside of the arena. Ledecky took one look at herself on the building, whipped out her smartphone and snapped a selfie.
“It’s cool; it’s different,” Ledecky said, adding, “It’s just amazing how U.S.A. Swimming does a great job of making things bigger and better than the last time, and I’m happy to be a part of it.”
The morphing of the trials from a lean, mean qualifying machine to a quadrennial celebration has drawn mixed reviews. There are people, led by coaches of elite swimmers, who bemoan the crowded lanes each morning during warm-ups and the long preliminary sessions, which threaten to bleed into the evening. And then there are those who love the idea that, once every four years, swimming has a “Super Bowl week,” as Chuck Wielgus, U.S.A. Swimming’s executive director, described it.
“There are eight people trying to make the Olympic team in every event,” Bob Bowman, the head United States Olympic men’s coach, said, referring to the finalists. “But it’s much more meaningful to everybody else now than it used to be.”
The 14,000-seat arena, in which two temporary 50-meter pools have been erected, is sold out every day, morning and evening, for the first time since the trials moved here in 2008. More than 140 all-session poolside “Victory Row” seats, priced at $1,150 apiece, were made available, and they also sold out.
“Hearing the seats are sold out is amazing,” said the 11-time Olympic medalist Ryan Lochte, who will try to make his fourth Olympic team. “It’s going to be loud. It’s going to be crazy. The last couple Olympic trials, we had fireworks; we had fire. It’s unbelievable.”
Rowdy Gaines, who won three gold medals at the Los Angeles Olympics and is part of NBC’s television coverage at the current trials, beat out 49 swimmers to win the 100-meter freestyle at the 1984 trials. He likes that about twice as many competitors (98) are in the event in 2016.
“It’s a good way to build exposure for the sport,” Gaines said. “Those swimmers in the early heats, they are going to go back home and tell their friends they swam at the Olympic trials.”
He added, “I can’t tell you how many people come up to me on my travels and tell me someone from their club has a shot at making the Olympics because he’s going to the trials.”
According to statistics provided by U.S.A. Swimming, the number of year-round athlete members from Midwestern Swimming, the sport’s regional governing body, has increased by nearly 50 percent since the trials were held in Omaha for the first time in 2008.
Conor Dwyer was 19 years old and had little experience on the national stage when he competed in the 100 and 200 freestyles at the 2008 trials. He was hooked from the opening night, where he had a front-row seat for the 400 individual medley duel between Michael Phelps and Lochte.
“It opened my eyes to how big a swimming competition can be,” Dwyer said.
In 2012, Dwyer qualified for the 4×200 freestyle relay along with Phelps, Lochte and Ricky Berens. The relay team won the gold at the London Games, where Dwyer also finished fifth in the 400 freestyle.
“If I wasn’t there in 2008, maybe I wouldn’t have had that goal to come back four years later and race those guys,” Dwyer said. “It does help people that you might not think have a shot right now, but four years down the road, you never know.”
Four years ago, Dressel said, he chose to sit by himself in the stands, away from his parents and coach, and observe how some of the best swimmers in the world went about their business. “I was in awe of everything,” he said. “That week, making the team one day became a goal of mine.”
An earlier version of this article referred incorrectly to the 2012 Olympic relay for which Conor Dwyer qualified. It was the 4×200, or 800-meter, freestyle relay — not the 4×800 relay.